1. Field of the Invention
The present invention relates generally to digital cameras and computer systems and more specifically to the operational capabilities of a digital camera tethered to a computer system.
2. Description of Relater Art
The digital camera has recently been developed as a portable system that acquires and stores digital still images in electronic form. The images may be used in a number of different ways, such as being displayed in an xe2x80x9celectronicxe2x80x9d photo album or used to embellish graphical computer applications. The digital camera has a user interface much like a conventional chemical film camera, but the images are captured and stored entirely using electronic solid state circuitry and image processing techniques.
A typical digital camera has an electronic image sensor that receives incident light reflected from an object or scene through an optical interface. The optical interface may include a lens system, an aperture mechanism, and perhaps a light filter. The sensor can typically be implemented as an array of charge coupled device (CCD) or complimentary metal oxide semiconductor (CMOS) photo-detecting circuits that create light-generated signals in response to the incident light. Analog signals from the sensor are converted into digital format by an analog-to-digital (A/D) converter and are then further processed by logic circuitry and/or a programmed processor to yield a captured digital image of the object or scene. The captured image is temporarily stored in internal random access memory (RAM) and may then also be stored in a removable local memory aboard the camera. The internal RAM stores a single image but the removable local memory may store a number of images. In addition, images may be transferred to a computer that is linked to the digital camera for storage as electronic files, for display to a user, for further graphical and image processing to improve the image quality, and for use with other graphics software.
Most purchasers of digital cameras have access to a personal computer (PC) system for viewing the still images. Therefore, such purchasers might also enjoy using their digital camera to communicate with another person, such as in a videoconferencing application with another computer in order to both see and hear the other person. However, most digital cameras are typically configured to provide only still images. Similarly, cameras used for videoconferencing typically do not operate as a still camera when disconnected from the computer. In response to these limitations, a digital camera and associated image processing architecture have been developed that permits xe2x80x9cdual modexe2x80x9d use of the camera for both video, where the camera may be linked (xe2x80x9ctetheredxe2x80x9d) to a computer for video purposes, and operated portably for still image capture. Such a system operates to provide still and video images through the same signal processing system, thereby reducing the cost to the consumer of purchasing separate still and video cameras.
However, such dual mode cameras have an inherent limitation in that the still image capture mode is used only when the camera is being operated in a portable, non-video manner. When the camera is used in the video mode (such as when it is connected to a PC for videoconferencing), the series of captured images comprising the video frame sequence overwrite any temporal still image which might be captured in the camera and stored in its internal RAM, thereby rendering impossible concurrent video streaming and still image capture operations.
Thus, a method and apparatus for providing concurrent video streaming and still image capture operations in a digital camera tethered to a computer is desired that overcomes the deficiencies and limitations of the prior art without adding to the cost of the camera.
An embodiment of the present invention is a method of capturing a still image during video streaming operations of a digital camera tethered to a computer system. The method includes the steps of pausing video streaming operations, capturing a still image by the digital camera, transferring the still image from the digital camera to the computer system, and resuming video streaming operations.
Another embodiment of the present invention is an apparatus for capturing a still image during video streaming operations of a digital camera. In a system having a digital camera tethered to a computer system by a bus, the apparatus includes a camera device driver executing on the computer system to pause video streaming operations, to request the capture of a still image by the digital camera, to request the transfer of the captured still image from the digital camera to the computer system, and to resume video streaming operations; and a bus interface driver coupled to the camera device driver and the bus to communicate commands and data between the camera device driver and the digital camera over the bus.